Cushioning of the handle of compressed air hammers



sept. 11, 1934. F. um 1,973,432

CUSHIOHING 0F THE HANDLE OF COMPRESSED IR HAMMERS Filed Nov. 29. 1932 ZSheetS-Slieet 1 I y' a www yf F. FAUDI 1,973,432;4 CUSHIONING OF THE HANDLE OF COMPRESSED 'AIR HAHUERS- l Sept. 1l, 1934.

Filed Nov. 29. 1952` z'sneets-sheet 2 30 piston during j'atented Sept. 1 1,- '1934 oUsHroNlNG oF THE HANDLE or i coMPnEsssn am Fritz Faudi, Dusseldorf-Oberkassel, Germany, as-

signor to A.

Oberkassel, Germany, a partnership o! Germany Application November 29, 1932, serial No, 644,81

, In Germany MayV 21, 1932 s claims. (ci. 267413 In the cushioning of the handle on compressed air hammers according to my patent application Ser, Nr. 600,500 the recoil ci the main hammer housing relatively to the handle is 'cushioned by throttling the return or the compressed air to the compressed air mains and the consequent moderately risingincrease in the ccmpressed air tension increases the total braking pressure on vthe piston rod carrying the handle which piston rod carries a piston reciprocating in a cushioning cylinder inthe hammer housing. The pressure is such that at the end of the possible cushioning path the cushioned members are separated from one another by a cushion of 5 compressed air which is, as far as possible, so completely trapped that metal to metal contact is impossible, even when violent recoil has to be cushioned.

An object vof the present invention is to provide a handle cushioning mechanism for pneumatic hammers providing a cushioning action which increases by successive steps.

'Ihe invention consists in providing cushioning mechanism comprising a cushioning piston reciprocably mounted in a cylinder in the `pneumatic hammer housing, said cylinder having a compressed air inlet, a piston rod connecting the cushioning piston to the handle of the pneumatic hammer, and means cooperating with the a cushioning stroke thereof for successively entrapping and compressing, separate cushioning volumes of compressed air.

A simple example oi construction of a handle cushioning arrangement of this type is shown in the drawings.

Figures 1, 2. 2a, 2b, 3, 3a, 4 and 5 show several forms of construction partly in section of the'arrangement, according to the invention.

Fig. 3h isafpart sectional view taken on a 40 plane at right angles to the plane of the section shown in Fig. 3.

' Referring to Figure 1 a is the hammer houslng containing the hammer mechanism, b is the hammer housing which surrounds the head chamber c and contains the cushioning compressed air. The transverse wall d separates the head chamber c from the the housing a.

The passage e connects. the head chamber with the working air oi the compressed air main or the compressor air accumulator. The plunger-like piston f carries the handle g. The piston J4 is shown to the left of the centre line in its extreme outward position, in which, by the compressed air loading its free piston surmain cylinder in the ilnal compressed air face, it is pressed into the head chamber c and in which it isheld when the hammer is connected with the main, but is not in operation. When violent `oscillations of the parts cushioned bythe compressed air occur, the piston ,f w can passinto the position shown to the right of the centre line, namely the opposite extreme position. In this position it has passed beyond the shoulder bf formed at the end of the head chamber, and separates a part oi the compressed 35 air in the head chamber which in the meantime has been subjected to` high tension, to form a true compressed air cushion between the `end surface of the piston, the surface oi' the partition d and the walls of the cylinder formed at the narrowed part of the head chamber over this partition.` Now the invention consists in that, without detriment to the presence of the compressed air cushion, when very great oscillations of the parts occur, such a cushion is formed even sooner in the course o1' the travel of the piston relative to the'housing, when both parts, as the hammer is pressed or being operated, are moved towards each other. The separation of the compressed air Ior the special compressed air cushion, may occur at the beginning of the relative movement of the piston, just after or when it is Sill .in a centre position.

According to` Figure 2 the special compressed 85 air cushion comes into operation for example, not in the iirst moment of the movement, but when it has proceeded a certain amount. Leit ot the-centre line, the relative initial position of the parts is shown, and on the right the final position. The piston contains the cylindrical cavity h which is coaxial with an auxiliary piston f ilxed on the partition d. If one imagines, in the cushioning, the piston f moving relativoli/'fromv the initial to the nal position, then 95 the whole piston area is loaded at rst by the compressed air in the head chamber. Then the compressed air is shut oit from a part of the piston by the entry oi the auxiliary piston f in the piston cavity h, and on the further forward movement of the piston, is compressed as a compressed air cushion. Its resisting pressure increasing progressively is added to the thrust which results from the free piston surface and the moderately increasing air pressure in the head chamber. When the piston reaches the projection b at the end of the head chamber, cushion is formed as described with reference to Figure 1, and the total loading oi the piston is now composed of and the additional compressed air cushion which has already previously become effective in the cavity h of the piston f. The elements serving to form this additional compressed air cushion, the cavity h and the auxiliary piston j' may, of course, also be arranged in a reverse order to that described--the piston j' canbe fixed to the main piston j and the cavity h may be arranged in the partition d, as shown in Fig. 2b.

The two members may also, at the outset, overlap each other in such a manner that the piston f' even in the initial position, is entered in the cavity h. n

The inter-engagement of the two parts than at the same time serves for the mutual guiding and for emcient trapping of the compressed air in the cavity h from the beginning. The trapping is in any case favored by the cylindrical smooth Walls and by the possibility thereby'presented of exact construction and fitting. Figure 2 shows this form of construction. The original connection between the quantity of compressed air separated for forming the cushion and the compressedair contained in the head chamber is established by a central boring in the auxiliary piston f. andby passages leading radially therefrom in one plane and at a distance from the end of the auxiliary piston f' and passing through the piston or the like. Its outlet position, that is, the movement in which it is lapped by the inner casing'surfaceof the hollow cylinder h, then decides the beginning of the action of the compressed air cushion introduced into it.

In the embodiment of the invention accor -to Figures 2 and 2a already described it was assumed that only one of the final compressed aircushions was introduced. Two or more additional compressed air cushions may be introduced, of which one after the lother is formed at previously determined distances and whereby those freshly produced in each case comesrinto operation therewith or with that `previously formed.

In this arrangement the same members suitable for forming a compressed air cushion, as described above, may be used, namely so that besides those located coaxially with the centre line of the hammer, or'without such, similar pairs of members are arranged distributed about the centre line of the relatively movable parts facing one another. Figs. 3 and 3a show an example. In this case four cylindrical bores are formed in the piston and opposite' them on the separating floor four suitably' formed solid cylinders j are rigidly mounted. According to the example the construction is such vthat the bores and the solid cylinders are arranged symmetrically in pairs with respect to the longitudinal axis of the head chamber, each bore of one pair and consequently each cylinder of the corresponding pair of cylinders being arranged diametrically. In the formation of the compressed air cushion iirst one pair come into operation followed by the other pair when the piston has travelled a. predetermined distance in relation to the housing.

. Instead of the compressed air ct'i'shioning elements being distributed over the surface oi thepiston or of the partition forming the floor 'of the head chamber, and constructing the compressed air cushioning elements as separate members in the form of cylindrical bores and cylindrical bpdies filling them the same purposek -ber containing the compressed air into two 95 is advantageously attained and the manufacture of the parts is facilitated, by the pairs of ele-l ments serving to form'two or more compressed air cushions before the formation of the iinal compressed air cushion, being formed as annular cylindrical recesses and projections, which surround each other concentrically. 1

,Such4 forms of construction are shown in Figure 4. `Figure 5 also shows an example of this.

In Figure 4 the projections and the recesses are 85 separated from leach other annularly and in Figura 5 they form step-like shoulders.

The two examples according to Figures 4 and 5 show, moreover, 'a form of construction in which the arrangement of additional compressed l l air cushions is used wherein a differential piston, by means of a trick piston rod, carries the handle. In this arrangement the piston head of the diiferential piston divides the head chamchambers, the main cushioning chamber c on the freesuxface vand the damping chamberA` c" on the surface reduced by the piston rod.

I claim: l

l. A handle cushioning v'mechanism compris# 100 ing a cushioning cylinder' having a compressed 4 air inlet, a piston reciprocably mounted in the cylinder, a piston rod connecting the cushioning piston with the handlesa Shoulder in the cylinder arranged between its lower end and the inlet. `m5

saidshoulder cooperating with the piston to entrap a cushioning volume oi compressed air, a plug extending upwardly from the bottom` of the cushioning cylinder and permanently engaging a corresponding cavity in the bottom of me.

cushioning. piston, said plug having a port perlmitting compressed air to enter said cavity during the first portion of a cushioning stroke of the piston and being sealed by said piston to entrap a separate volume of cushioning air in -11 said cavity before the lpiston reaches the shoulder.

2. A handle cushioning mechanism comprising a cushioning cylinder having a compressed air inlet, a piston reciprocably mounted in the cylinder, a piston rod connecting the cushioning piston with the handle, a shoulder in the cylinder arrangedbetween its lower end and the inlet, said shoulder cooperating with the piston to en\ trap a cushioning volume of compressed air, a

plurality of concentrically arranged projections of different height in the bottom of the cushioning cylinder cooperating with a plurality of corresponding concentrically arranged cavities in the bottom of the cushioning piston to successively entrap separate cushioning volumes of compressed air before the piston reaches the shoulder.

3. AA handle cushioning mechanism comprising a cushioning cylinder having a compressed air inlet, a piston reciprocably mounted in the cyl- `inder, apiston rod connecting the cushioning piston with the handle, a shoulder in the cylinder arranged between its lower end and the inlet, said shoulder cooperating with vthe piston to entrap a cushioning volume of compressed air, a stepped auxiliary piston arranged in the ,bottom of the cushioning cylinder and cooperating -with a corresponding stepped cavity in the bottom of the cushioning piston to successively entrap separate cushioning volumes of compressed air before the first mentioned vpiston reaches the shoulder.

4. A handle cushioning mechanismcompris- ,Y ing a cushioning cylinder having a compressed 15 air inlet, a main piston recprocably mounted in'the cylinder and having a cavity therein, a piston rod connecting the cushioning piston with the handle, and an auxiliary piston in the cylinder cooperating with the cavity in the first-v mentioned main piston, said cylinder having means therein so that the auxiliary piston and the cavity form a separate cushioning volume of compressed air before the main piston makes an air cushion in the cylinder by the elimination of the influence of the compressed air inlet in the cylinder.

' 5. A handle cushioning mechanism comprising a cushioning cylinder having a compressed air inlet, a piston reciprocably mounted inthe cylinder and forming therewith the parts V to be cushioned, a piston rod connecting the. cushioning piston with the handle, a shoulder in the cylinder placed between its'lower end and `the inlet, said shoulder cooperatingwith the piston to entrap a cushioning volume .of compressed air, and an auxiliary piston on and a cooperat-A` ing cavity in said kparts to be cushioned so arranged that the auxiliary piston will enter the.

cavity and entrap therein a separate cushioning volume'of compressed ,air before the firstmentioned piston reaches the' shoulder.

6. A handle'cushioning mechanismcomprising a cushioning cylinder having a compressed air inlet, a piston reciprocably mounted in tli'e cylinder, a piston rod connecting the cushioning piston with the handle, and an auxiliary piston in the cylinder 'cooperating with the piston and.

a `cavity into which it ts, said cylinder having means therein so that the auxiliary piston and the cavity form a separate cushioning volume of compressed air before the main piston makes an air cushion inthe cylinder by eliminating the iniluence of the compressed air inlet in the cylinder?.

' 1. A handle lcushioning mechanism according t to claim '6, in which the vauxiliary piston is of smaller diameter than the diameter of the main piston.

8. A handle cushioning mechanism comprising a cushioning cylinder having a compressed air inlet, a *pistonreciprocably mounted in thel ,cylindenandani auxiliary pistonin the cylinder cooperating with the piston and a cavity into which it fits, said cylinder having means therein sev so that the auxiliary piston'and the cavity form a. separate cushioning volume of compressed air before the main piston makes an air cushion in the cylinder by eliminatingfthe influence 'of the compressed air inlet in the cylinder.

FRITZ FUiJI. 

